PYTHON PROGRAMMING WITH WEB FRAMEWORKS – CSE304 This presentation contains the concepts related to work with data types and variables, numeric data, string data
Data Types • When you develop a Python program, you work with variables that store data. • A data type defines the type of data for a value. • 3 types of basic Python data types: 2
3
Data Types 4
Data Types • How to code literal values (there are two literals) – String literal (enclose the characters of the string in single or double quotation marks). – Numeric literal (code the number without quotation marks). • You can assign a value of any data type to a variable. • An assignment statement uses the equals sign (=) to assign a value to a variable. • The value can be a literal value, another variable, or an expression like the arithmetic expressions. 5
Variables • A Python variable is a symbolic name that is a reference or pointer to an object. • Once an object is assigned to a variable, you can refer to the object by that name anywhere inside the program. • How to name variables ? – Give meaningful names. That means that it should be easy to tell and easy to remember. – Avoid abbreviations. – Use underscore notation. (example: tax_rate) – You may use camel case. (example: taxRate) 6
Rules for naming variables • A variable name must begin with a letter or underscore. • A variable name can't contain spaces, punctuation, or special characters other than the underscore. • A variable name can't begin with a number, but can use numbers later in the name. • A variable name can't be the same as a keyword that's reserved by Python. 7
Python Keywords 8
Python 3.9.X Keywords List • 36 keywords 9
Python's arithmetic operators 10
How to work with numeric data • The order of precedence for arithmetic expressions: • Examples that show the order of precedence and use of parentheses 11
How to work with numeric data • An arithmetic expression consists of one or more operands that are operated upon by arithmetic operators. • No need of spaces before and after the arithmetic operators. • When an expression mixes integer and floating-point numbers, Python converts the integers to floating- point numbers. • Use parentheses to clarify the sequence of operations (when multiple operators are used). Otherwise, Python applies its order of precedence. 12
How to work with numeric data • Compound assignment operators provide a shorthand way to code common assignment statements. • Besides the compound operators in the table. Python offers /=. //=. %=, and **=. • When working with floating-point numbers, be aware that they are approximations, not exact values. This can cause inaccurate results. 13
Other Operators • Comparison Operators: !=, ==, <, <=, >, >= • Unary Operators: Unary plus (+) Unary minus (-) • Bitwise Operators &(AND), |(OR), ^(XOR), ~(One's Compliment), << (Left Shift), >>(Right Shift) 14
Other Operators • Logical Operators: and, or, not • Assignment Operators: =, +=, -+, *=, /=, //=,... • Membership Operators: in, not in • Identity Operators: is , is not 15
Operator Precedence • Parenthesis – () • Exponentiation – ** • Compliment, unary plus and minus – ~, +, - • Multiply, Divide, modulo – *, /, % • Addition and Subtraction – +, - • Right and Left Shift – >>, << • Bitwise AND – & • Bitwise OR and XOR – |, ^ • Comparison Operators – ==, !=, >, <, >=, <= • Assignment Operator- = 16
How to use the interactive shell for testing numeric operations • Demo 17
How to work with string data • You can also create an empty string by coding a set of quotation marks with nothing between them. • And you can assign a new value to a string variable. This works the same way it does with numeric variables. 18
How to work with string data 19
Common escape sequences • you can use escape sequences to include certain types of special characters such as new lines and tabs. • You can also use escape characters to include special characters such as quotation marks and backslashes. 20
Common escape sequences 21
Common escape sequences 22

1.4 Work with data types and variables, numeric data, string data.pptx

  • 1.
    PYTHON PROGRAMMING WITH WEBFRAMEWORKS – CSE304 This presentation contains the concepts related to work with data types and variables, numeric data, string data
  • 2.
    Data Types • Whenyou develop a Python program, you work with variables that store data. • A data type defines the type of data for a value. • 3 types of basic Python data types: 2
  • 3.
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    Data Types • Howto code literal values (there are two literals) – String literal (enclose the characters of the string in single or double quotation marks). – Numeric literal (code the number without quotation marks). • You can assign a value of any data type to a variable. • An assignment statement uses the equals sign (=) to assign a value to a variable. • The value can be a literal value, another variable, or an expression like the arithmetic expressions. 5
  • 6.
    Variables • A Pythonvariable is a symbolic name that is a reference or pointer to an object. • Once an object is assigned to a variable, you can refer to the object by that name anywhere inside the program. • How to name variables ? – Give meaningful names. That means that it should be easy to tell and easy to remember. – Avoid abbreviations. – Use underscore notation. (example: tax_rate) – You may use camel case. (example: taxRate) 6
  • 7.
    Rules for namingvariables • A variable name must begin with a letter or underscore. • A variable name can't contain spaces, punctuation, or special characters other than the underscore. • A variable name can't begin with a number, but can use numbers later in the name. • A variable name can't be the same as a keyword that's reserved by Python. 7
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    Python 3.9.X KeywordsList • 36 keywords 9
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  • 11.
    How to workwith numeric data • The order of precedence for arithmetic expressions: • Examples that show the order of precedence and use of parentheses 11
  • 12.
    How to workwith numeric data • An arithmetic expression consists of one or more operands that are operated upon by arithmetic operators. • No need of spaces before and after the arithmetic operators. • When an expression mixes integer and floating-point numbers, Python converts the integers to floating- point numbers. • Use parentheses to clarify the sequence of operations (when multiple operators are used). Otherwise, Python applies its order of precedence. 12
  • 13.
    How to workwith numeric data • Compound assignment operators provide a shorthand way to code common assignment statements. • Besides the compound operators in the table. Python offers /=. //=. %=, and **=. • When working with floating-point numbers, be aware that they are approximations, not exact values. This can cause inaccurate results. 13
  • 14.
    Other Operators • ComparisonOperators: !=, ==, <, <=, >, >= • Unary Operators: Unary plus (+) Unary minus (-) • Bitwise Operators &(AND), |(OR), ^(XOR), ~(One's Compliment), << (Left Shift), >>(Right Shift) 14
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    Other Operators • LogicalOperators: and, or, not • Assignment Operators: =, +=, -+, *=, /=, //=,... • Membership Operators: in, not in • Identity Operators: is , is not 15
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    Operator Precedence • Parenthesis– () • Exponentiation – ** • Compliment, unary plus and minus – ~, +, - • Multiply, Divide, modulo – *, /, % • Addition and Subtraction – +, - • Right and Left Shift – >>, << • Bitwise AND – & • Bitwise OR and XOR – |, ^ • Comparison Operators – ==, !=, >, <, >=, <= • Assignment Operator- = 16
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    How to usethe interactive shell for testing numeric operations • Demo 17
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    How to workwith string data • You can also create an empty string by coding a set of quotation marks with nothing between them. • And you can assign a new value to a string variable. This works the same way it does with numeric variables. 18
  • 19.
    How to workwith string data 19
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    Common escape sequences •you can use escape sequences to include certain types of special characters such as new lines and tabs. • You can also use escape characters to include special characters such as quotation marks and backslashes. 20
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